<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .content{
            display: flex;
            width: 60%;
            height: 100px;
            background-color: pink;
            margin:0px auto;
        }
        .content div:nth-child(1){
            width: 100px;
            height: 100px;
            background-color: green;
        }
        .content div:nth-child(3){
            width: 100px;
            height: 100px;
            background-color: blue;
        }
        .content div:nth-child(2){
            flex:1;
            background-color: yellowgreen;
        }
    </style>
</head>
<body>
    <div class="content">
        <div></div>
        <div></div>
        <div></div>
    </div>
</body>
</html>